The Sellwood’s uncommon construction gives it historic value. As such, the National Historic Preservation Act specifies the county must court potential buyers before demolishing the bridge.

The county will post for-sale ads in The Oregonian and the Daily Journal of Commerce this week.

County leaders aren’t anticipating a flood of interest.

Although the old bridge could be bought for a bargain, the buyer would pay a hefty price to move it to its new home. For perspective, county spokesman Mike Pullen said, “we spent more than a million dollars to move it 60 feet” last year to give construction crews room to build its replacement.

Moving any bridge is expensive. The Sellwood has the added complications of a lead-based paint coating that must be contained during the move and a 1,091-foot truss span that would need to be cut into smaller pieces before transport to a new home.

“That’s a big extra cost,” Pullen said.

Cutting the truss span would also compromise the main feature that makes the Sellwood Bridge historic.

The Sellwood is the Oregon’s only bridge with a four-span continuous truss holding up the roadway, and the only known highway bridge with such a distinction. That qualifies it for the National Register of Historic Places. Although the bridge is not actually listed on the register, simply qualifying is enough to trigger the federal rule that requires the county to offer the bridge for sale.

Even without the Sellwood’s unique complications, buying and moving a bridge is an undertaking rife with costs and complications.

Take, for example, the 2006-2008 project to replace the Sauvie Island Bridge. The river crossing was deemed historic, so the county had to put it up for sale. Then-Portland Commissioner Sam Adams crafted a plan to repurpose it as a bike and pedestrian route over Interstate 405. The plan was later abandoned due to cost.

Pullen said so far, one person has expressed interest in the Sellwood Bridge. A retired Oregon Department of Transportation employee contacted county officials to suggest turning it into a bicycle and pedestrian link between Lake Oswego and Milwaukie.

“It’s not out of the realm of possibility that a private individual, if they had unlimited resources, could buy it,” Pullen said. But more likely, he said, the bridge will be demolished.

If no buyer comes forward by Sept. 12, the county will turn the Sellwood over to the contractor in charge of building the new Sellwood Bridge. The contractor will sell the bulk of the the steel-and-concrete structure to a recycling company.

A few pieces, such as the plaque that commemorates the original bridge’s 1925 completion, will be saved. They’ll join a host of bridge artifacts already on display in the county bridge office. Plaques will be placed on the new bridge to honor the old structure that once stood in its place.